The Hidden Room is an optional room in Luigi's Mansion and its Nintendo 3DS version.

Description[]

The Hidden Room is a small room with seven red treasure chests, three of which contain treasure. The room's floor and walls are golden, and the entire room sparkles with gold dust. The Hidden Room also two vases and a mirror on the south wall only visible when using the Game Boy Horror.

The Hidden Room is similar to the Sealed Room, which also has a sparkling, golden wall, and both rooms are optional and hidden.

In Luigi's Mansion[]

The Hidden Room first is first accessible during Area Two. It can be accessed by inspecting the mouse hole in the Butler's Room with the Game Boy Horror, activating a wind-like vacuum that directly sucks Luigi into the Hidden Room.

Four of the treasure chests each contain a Flash (each replaced with a Ghost Guy in the PAL releases' and Nintendo 3DS version's Hidden Mansion). After Luigi captures every Flash, the room's lights turn on, and a green treasure chest appears; this is the only treasure chest that contains a Blue Stone, a Green Stone, and a Red Stone.

During the blackout, two Blue Twirlers, one Grabbing Ghost, and several Bats appear here, but unlike before, none of them are revealed from a treasure chest. However, one of the treasure chests has a Speedy Spirit, exclusively appearing here during the blackout.

[Edit] / Nintendo 3DS version
Main characters	Main characters	Luigi • Professor E. Gadd • King Boo • Mario • Gooigi†
Ghosts	Normal	Bat • Black Bogmire • Blue Blaze • Blue Twirler • Boo • Bowling Ghost • Ceiling Surprise • Elemental Ghosts (Fire • Water • Ice) • Flash • Flying Fish • Garbage Can Ghost • Ghost Guy • Gold Ghost • Gold Mouse • Grabbing Ghost (Cinema • Mirror • Red) • Mouse (Blue • Purple) • Mr. Bones • Purple Bomber • Purple Puncher • Shining Ghost • Spark • Speedy Spirit • Temper Terror • Waiter
	Portrait Ghosts	Biff Atlas • Bogmire • Boolossus • Chauncey • Clockwork Soldiers • Floating Whirlindas • Henry and Orville • Jarvis • King Boo • Lydia • Madame Clairvoya • Melody Pianissima • Miss Petunia • Mr. Luggs • Nana • Neville • Shivers • Sir Weston • Slim Bankshot • Spooky • Sue Pea • Uncle Grimmly • Vincent Van Gore
	Other	Polterpup†
Rooms	Professor E. Gadd's Lab	Gallery • Portrificationizer Chamber • The Lab • Training Room
	Area one	Anteroom • Balcony • Foyer • Master Bedroom • Nursery • Parlor • Study • Wardrobe Room
	Area two	Ball Room • Bathroom • Boneyard • Butler's Room • Conservatory • Dining Room • Graveyard • Hidden Room • Kitchen • Laundry Room • Mirror Room • Storage Room • Washroom
	Area three	Astral Hall • Balcony • Bathroom • Billiards Room • Bottom of the Well • Courtyard • Fortune-teller's Room • Nana's Room • Observatory • Projection Room • Rec Room • Safari Room • Tea Room • The Twins' Room • Washroom
	Area four	Armory • Artist's Studio • Breaker Room • Cellar • Ceramics Studio • Clockwork Room • Cold Storage • Guest Room • Pipe Room • Roof • Sealed Room • Secret Altar • Sitting Room • Telephone Room
Items	Items	Bill • Blue Diamond • Coin • Element Medal (Fire • Ice • Water) • Gold Bar • Gold Bone† • Gold Diamond • King Boo's Crown • Mario's Glove • Mario's Hat • Mario's Letter • Mario's Shoe • Mario's Star • Pearl • Red Diamond • Stone (Blue • Green • Red)
Objects	Regular	Bomb • Boo Ball • Cheese • Mirror
	Hazards	Fake door • Fire
	Equipment	Boo Radar • Flashlight • Game Boy Horror • Poltergust 3000 • Strobulb†
Other	Other	Ghost Portrificationizer • Ghost's heart • Luigi's Mansion • Luigi's NEW Mansion • Mario's Painting
Items marked with † are exclusive to the Nintendo 3DS version.